Grooved fluid bearing bar

ABSTRACT

Process for forming a series of spaced, generally uniform, curved grooves of tapered configuration in a surface of a bar intended for use in a fluid bearing track structure or the like, and the grooved bar which results from utilizing such process. Material is cut or ground from the bar surface by a rotary cutter or cylindrical grinder, the axis of rotation of which is set at compound angles and is inclined in the direction of movement of the bar and also in a direction transverse to such direction of movement. Each of the curved grooves progressively decreases in depth and width from one end thereof towards its other end to define a nozzle configuration. In the preferred embodiment illustrated, the bar being grooved is moved continuously beneath a continuously rotating cutter.

United States Patent [1 1 Lasch, Jr.

mi 3,796,466 1i Mar. 12, 1974 GROOVED FLUID BEARING BAR PrimaryExaminer-Richard E. Aegerter 75 Inventor: Cecil A. Lasch, Jr., LosAltos, Calif. Exammer'rH' Lane [73] Assignee: Industrial Modular Systems[57] ABSTRACT Corporation, Santa Clara, Calif.

Process for forming a serles of spaced, generally um- [22] Filed: June10, 1971 form, curved grooves of tapered configuration in a surface of abar intended for use in a fluid bearing [21] L935 track structure or thelike, and the grooved bar which Related US. Application Data resultsfrom utilizing such process. Material is cut or [62] Division of Ser.No. 852,216, Aug. 22, 1969, Pat. No. ground from the bar Surface y arotary Cutter 0r y- 3,631,758. lindrical grinder, the axis of rotationof which is set at compound angles and is inclined in the direction of[52] US. Cl. 302/29 movement of the bar and also in a directiontransverse [51] Int. Cl. B65g 53/04 to such direction of movement. Eachof the curved [58] Field of Search 302/2, 29, 31; 415/215 groovesprogressively decreases in depth and width from one end thereof towardsits other end to define a [56] References Cited a nozzle configuration.In the preferred embodiment il- UNITED STATES T N lustrated, the barbeing grooved is moved continu- 2,4s0,s07 8/1949 DeVlieg 415/215 x Ouslybeneath a Commmusly rotanng cutter 9 Claims, 11 Drawing Figures GROOVEDFLUID BEARING BAR This application is a division of my formerApplication Ser. No. 852,216 filed Aug. 22, 1969, now U.S.

' Pat. No. 3,631,758, issued Jan. 4, 1972.

Articles.

BACKGROUND OF THE INVENTION l. Field of the Invention This inventionrelates generally to the field of forming grooved bars usable ascomponents of track structures employed in fluid bearing transportsystems. More particularly, this invention relates to the field of fluidbearing bars having grooves therein through which a fluid bearing mediumis passable for supporting and moving articlesalong a fluid bearingtrack structure of which such bars are a part, and to a simplified,improved and inexpensive process for forming grooves in such bars.Although the subject process is particularly effective in conjunctionwith the manufacture of grooved bars for use in fluid bearing systemssuch as disclosed in the aforementioned application, the utility of thisinventionis not limited to such purpose and its utility extends to otherareas as well.

2. Description of the Prior Art Fluid bearing track structures ofvarious types have been generally known in the art heretofore, and thefollowing patents disclose track structures which are exemplary of theprior art: Hazel US. Pat. No. 2,778,691, dated Jan.22, 1957; Cole U.S.Pat. No. 3,103,388, dated Sept. 10, 1963; and Coville US. Pat. No.3,318,640, dated May 9. 1967. Prior known fluid bearing track structuresof the type exemplified by these patents, however, do not contemplate ordisclose the improved grooved bar construction disclosed herein or thesimplified and inexpensive process of grooving such bars similarlydescribed herein.

So far as is known, grooved bars of the construction disclosed hereinhave been unknown prior to this invention or to the invention embodiedin the related features described in the aforementioned application.Speciflcally, fluid bearing bars having a series of curved grooves in asurface thereof, each of which is formed generally with a tapered nozzleconfiguration defined by one end which is larger than its opposite end,have been unknown prior to this invention. Similarly, the numerousadvantageous features of the process of this invention have been unknownin the art to which this invention pertains.

SUMMARY OF THE INVENTION grooves are formed in a bar surface, each ofwhich is of varying dimension from one end thereof towards the other andto a process for grooving such surface.

Still more particularly, this invention relates to a grooved bar havinga series of grooves therein each of which varies in both width and depthfrom one edge of a grooved surface to the other edge thereof, wherebyeach such groove is imparted with a nozzle. shaped configuration. Inthat connection, tlhe invention specifically relates to an improved andsimplified process for grooving a series of bars in which a rotarycutter or grinder is utilized to form individual tapered grooves duringa portion of each revolution of the cutter.

During such utilization of the grooving tool, .the bar being grooved isadvanced in conjunction with rotation of the cutter so that successivegrooves are formed in the surface in response to such bar movement. Inthe illustrated embodiment, the bar, being grooved is moved continuouslybeneath a continuously rotating cutter. However, if a grinding tool isutilized, advancement of the bar is incremental in conjunction withformation of each groove. The grooving tool is rotated about an axiswhich is inclined in two directions relative to the vertical so thatengagement of the tool with the bar surface during only a portion ofeach revolution thereof is insured. Thus grooves are formed to extend inonly one uniform orientation along the length of the bar surface desiredto be grooved.

In the apparatus schematically illustrated herein, a rotary cutter,which may form part of a conventional milling machine,is utilized. Suchcutter includes an offset cutting point or edge of predeterminedconfigura tion chosen in accordance withthe configuration of the groovecross-section desired for a given bar. In such arrangement, the barbeing grooved is mounted in the milling machine and advanced along apredetermined ter may perform its intended function as the bar movestherealong.

In the specific bar embodiment illustratedherein by way of example, eachbar being grooved includes a longitudinal channel which bisects the barinto two generally planar sections, one of which lies along each side ofthe channel. Such channel forms a fluid passage to be operativelyconnected with a plenum or like chamber in a fluid bearing trackstructure. The grooves formed in the bar are located in communicationwith such channel and extend from one edge of the surface defined by thechannel to an opposite edge of the surface from which the grooves exitat a predetermined angle. Such exit angle may be controlled withinprecise limits by the grooving process disclosed herein by properorientation of the axis of the rotary cutter relative to the axisofdirection of movement of the bar therebeneath. Groove exit angles maybe selected, as may groove depth variations and the like, so thatgrooved bars tailored to meet specific needs may be readily andinexpensivelyformed on available milling machinery. I i i From theforegoing, it shouldbe understood that objects of this inventioninclude: the'gprovision of an improved process for forming a series ofcurved generally uniform grooves in a surface of abar; the provision ofan improved grooved bar in which grooves of varying dimension are formedin sequence along thelength of a surface being grooved; the provision ofan improved grooves in a surface thereof; the provision of an improvedand simplified process for forming a series of spaced curved grooves ina bar surface by removing material of such bar from such surface inaccordance with a predetermined program; the provision of an improvedfluid bearing bar structure in which individual grooves are formedhaving decreasing depths and widths from one end of each groove towardsthe other; the provision of a fluid bearing bar structure having curvedgrooves therein which are formed generally as segments of an ellipse;the provision of a bar structure in which the exit angles of the groovesmay be selectively varied in accordance with a predeterminedmanufacturing plan; and the provision of a bar grooving process in whichthe groove exit angle may be modified within wide limits to meetspecific needs.

These and other objects of this invention will become apparent from astudy of the following disclosure in which reference is directed to theattached drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view showing aportion ofa bar being grooved by the subject process.

FIG. 2 is a plan view of a portion of a grooved bar illustrating detailsof the construction of the individual grooves formed therein.

FIGS. 3, 4, and 6 are partial sectional views through the grooved bartaken in the planes oflines 33, 4-4, 5-5 and 6-6 respectively, of FIG.2.

FIG. 7 is a generally schematic plan view illustrating the path tracedby the cutting edge of a rotary cutter in relationship to the bar movingtherebeneath.

FIGS. 8 and 9 are generally schematic views illustrating the respectiveangles of inclination of the axis of rotation of the rotary cutterrelative to the axis of direction of movement of the bar being grooved.

FIG. 10 is an isometric view of one embodiment of a rotary cutter whichmay be employed in the subject process.

FIG. 11 is a sectional view illustrating one examplary utilization ofagrooved bar formed by the subject process in conjunction with cooperablecomponents in a fluid bearing track structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS I As noted previously, thisinvention has as an important aspect thereof the production of groovedbars, particularly bars well suited for use in fluid bearing trackstructures designed for the handling and transport of various and variedarticles, such as, by way of example, silicon and like wafers of thetype widely used in the electronics industry. In that connection,reference is directed to the aforementioned application for furtherdescriptions and exemplary showings of uses for such grooved bars.

It should be notedthat this invention is utilizable in conjunction withbars of various configurations and materials, such as metals, rigidplastics, or refractory mats, suitable for use in a given fluid bearingtrack structure installation. The configuration of such bars may vary tomeet particular needs but, in general, such bars are generallyrectangular in cross-section, frequently formed with longitudinalchannels therein which provide a main fluid flow passage extending alongthe length of the bar in communication with the tributary grooves whichexit at one edge of the bar over which articles being handled andtransported pass when such bar is positioned in a fluid bearing trackstructure.

Before describing details of the preferred procedure for grooving a barsurface as disclosed herein, reference is directed to FIGS. 1 through 6which illustrate the novel configuration of the grooves formed as fluidpassages through which article supporting and transporting fluid passeswhen such bar is utilized in a fluid bearing track structure. Thesubject bar, generally designated 1, includes a generally planar surface2 in which grooves are to be formed for the stated purpose. In theembodiment illustrated, one edge of surface 2 is defined by alongitudinally extending, main fluid flow channel 3 with its oppositeedge being defined by an edge surface 4 of the bar. As best noted fromFIG. 1, the bar is generally rectangular in cross-section with channel 3altering its regular cross-section in the area noted.

In the embodiment illustrated, a second generally planar surface 6 lieson the opposite side of channel 3. Surface 6 is generally coplanar withsurface 2 in which the grooves are formed for the purpose to bedescribed.

As seen from FIGS. 1 and 2, surface 2 is formed with a series of spaced,generally uniform grooves 7 each of which extends across surface 2 fromedge 8 to channel 3 to the aforementioned edge surface 4 of the bar.Each groove opens onto edge surface 4 at a predetermined exit angleselected in accordance with the nature of the articles to be supportedby fluid above such surface.

As noted from FIGS. 3 through 5, the cross-sectional configuration ofthe grooves 7 formed in the illustrated embodiment of the bar isgenerally trapezoidal in contour defined by a generally flat bottom andtapered side walls. It should be evident, however, that othergroovecrosssectional configurations may be utilized, such as circular,elliptical, triangular, or square. In a milling manufacturing process ofthe type described hereinafter, pre-selected groove cross-sectionalconfiguration may be easily accomplished by choosing a cutting toolhaving a cutting edge of the desired configuration to meet a particularneed.

It is an important aspect of this invention that the re spective groovesare formed with non-uniform dimensions from one end thereof to theother. That is, each groove 7 at its end which opens onto channel 3 islarger in cross-section than it is at its opposite end where it opensonto the edge surface 4 of the bar. Such dimensional variance iseffected by forming each groove with a depth and width whichprogressively decreases from its end adjacent channel 3 to its endadjacent the bar edge surface 4. Such dimensional variation imparts agenerally nozzle shaped configuration to each groove which adapts thesame for effective use in a fluid bearing track structure well adaptedfor supporting and transporting articles in the manner described in Ithe aforementioned application.

Each nozzle shaped groove preferably curves gradually and continuouslyfrom channel 3 to the bar edge 4. In that connection, in the embodimentillustrated in which the bars shown are formed by the grooving processto be described, each curved groove is formed generally as a segment ofan ellipse. However, it should be understood that other geometricalconfigurations for the grooves may be utilized also, such as arcs ofcircles and the like.

ever, it should be understood that the groove exit angle may be variedwithin wide predetermined limits with the relatively small exit anglesshown being preferred because of the substantial directional incrementimparted thereby to the fluid emanating therefrom for effectivelysupporting and moving articles to be carried across the bar edge 4. Exitangles within the range of approximately 1 to approximately 25 have beenfound suitable for most article handling and transporting functions,although larger exit angles up to or exceeding 90 also may be providedif required for particular purposes. The exit angle chosen will beselected in accordance with the type and configuration of the articlesto be transported, their weight and size the pressure of the supportingfluid to be utilized, and like factors.

Reference is now directed to FIGS. 1 and 7 through for an illustrationof an improved process for forming grooves of the type noted in a bar.It is an important feature of such process that it is capable of forminggrooves in only surface 2 without grooving surface 6 when a bar of thetype shown in FIG. 1 is being manufactured. Such surface groovingselectivity is made possible by the particular orientation of the axisof rotation of the cutter utilized as will be described hereinafter.

A rotary cutterof the type well suited for forming the subject groovesis illustrated by way of example in FIG. 10 and isdesignated 11. Suchcutter has an offset cutting point or edge 12 the configuration of whichdetermines the cross-sectional contour of the respective grooves to beformed in a given bar. Cutting edge 12 in the cutter illustrated isgenerally trapezoidal inconfiguration to form each groove 7 with thegenerally flat bottom and inwardly converging side walls shown in FIGS 3through 5. As previously noted, other forms of cutter edges also may beemployed if preferred.

It should be understood that cutter 11 may be mounted in a millingmachine for rotation at preselected speeds and about variable axes ofrotation in accordance with the results desired for a given groovingjob. The subject grooving process is readily effected by utilizing aflycutting technique on such a vertical milling machine. In that regard,the bar 1 to. be grooved is positioned and clamped to the automatic feedtableof the machine which is advanced longitudinally along apredetermined linear path at a continuous preselected speed: 3

Referring to FIG. 1, the axis of the path of movement a of the barthrough the milling machine is designated by ,arrowl6. By using amilling machine, quantities of grooved bars may be readily and veryinexpensively produced by relativelyunskilled labor. Importantly, thesubject process permits the formation of curved, tapered nozzle shapedgrooves having selectively variable exit angles as described previously.

As noted from FIGS. 1 8 and 9, the axis of rotation of cutter I1 isinclined in a predetermined manner. That is, such axis of rotation,designated 19, is tilted at a predetermined angle of inclinationrelative to the vertical, designated by numeral 18 in such figures. Inthe illustrated procedure, such inclination is effected in the samedirection as the axis of, movement 16 along which bar 1 is transported.Additionally, it has been found it will be noted that the cutter axis isinclined laterally in a direction towards channel 3 formed in the barbeing grooved, for the purpose to be described.

Thus, it will be understood that the axis of rotation 19 of the cutterincorporates therein both forward tilt as well as the transverse orlateral tilt as described.

Referring to FIG. 7, it should be noted that if the cutter were rotatedabout an upright axis cutter edge 12 would define a generally circularpath in a horizontal plane as indicated by dotted line 21 in suchfigure. However, because of the inclination of the axis of rotation 19of the cutter inthe manner described, the path of rotation in ahorizontal plane defined by cutter edge 12 is generally elliptical inconfiguration as noted by dotted line 22 in FIG. 1. If the bar being outwere maintained stationary'during the successive periods of engagementtherewith by the cutter edge, segments of an ellipse would be formed inthe bar surface. By' progressively and continuously moving the barduring rotation of the cutter, the generally elliptical configuration ofthe grooves cut in the bar surface may be selectively modified asdesired to meet a particular need.

The forward tilt of the axis of rotation of the cutter permits cutteredge 12 to rise above and clear surface 2 rearwardly of the groovespreviously formed so that all grooves formed extend in the sameorientation as noted in FIG. 1. That is, the cutter edge, because of thetilt of the axis of rotation, engages surface 2 during only a portion ofeach revolution of the cutter.

The transverse tilt of the axis of rotation of the cutter producesgrooves of decreasing depth and width as previously noted. That is, thelateral tilt of the axis of rotation causes cutter edge 12 to cut moredeeply into the bar adjacent channel 3 and gradually to rise upwardlyrelative to the surface 2' as the cutter approaches the edge surface 4of the bar. Thus, the tapered width and depth noted is automaticallyeffected. The amount of such taper may be selectively varied by alteringthe degree of transverse tilt of the cutter.

By properly positioning the axis of rotation 19 of the cutter relativeto bar surface 2, assurance can be given that the cutter edge will notengage the surface 6 on the opposide side of channel 3, thereby insuringthat grooves will be formed only in surface 2 where they are preferred.a

It should be understood from FIG. 7 that longitudinal movment of the barduring rotation of the cutter produces an elliptical cut of differentconfiguration than if the bar were temporarily held stationary duringcutting, By modifying the speed of movement of the bar relative to thespeed of rotationof the cutter, or by moving the center of rotationlaterally to the right or left from the point indicated in FIG. 7, theelliptical contour of the grooves may be increased or decreasedselectively, thereby also increasing or decreasingthe exit angle for therespective grooves relative toedge suiface 4 of the bar. In theillustrated embodiment, the axis of rotation of the cutter ispositioned, and the relative speeds of rotation and movement of thecutter and the bar are segrooved in illustrated fashion only and are notintended to be dimensionally accurate in that regard.

While it is preferred to move the bar continuously in the mannerdescribed, it should be understood alos that the bar may be moved inincrements timed with the rotation of the cutter. That is, if desiredthe bar may be held stationary during the time when the cutter point isactually engaged with and grooving the surface 2 of the bar. Suchprocedure is somewhat less desirable than that noted previously butcould be employed for special purposes and in a modified procedure, suchas when a grinding tool is employed.

As already noted, the degree of tilt imparted to the axis of rotation ofthe cutter may be varied to produce a given result. However, by way ofexample, inclinations of 2.5 in the forward direction and in thetransverse direction have been found effective for producing barssuitable for many needs.

FIG. 11 illustrates one examplary installation in which a grooved bar ofthe type described may be utilized as part of a fluid bearing trackstructure. In that regard, grooved bar 1 is held in engagement with aflat back up bar 26 by means ofa headed bolt 27 extending through therespective bars. Channel 3 in bar 1 is operatively connected with an airplenum (not shown) or other source of bearing fluidso such fluid maypass through the channel and then upwardly through the respective curvedgrooves 7 into engagement with articles to be supported on the edgesurface 4 of bar 1 and the corresponding aligned edge surface 28 of backup bar 26. The arrangement shown in FIG. 11, is merely illustrative andvarious other arrangements are contemplated to take full advantage ofthe novel construction of the grooved bars described herein.

It should be understood that by altering and preselecting the variablefactors noted previously that curved grooves of generally uniformconfiguration but having preselected curved contours ranging from arcsof circles to exaggerated segments of ellipses may be provided, and todefine exit angles selectable within wide predetermined limits, so thatbars capable of meeting widely varying needs may be produced.

Having thus made a full disclosure of this invention, reference isdirected to the appended claims for the scope of protection to beafforded thereby.

I claim:

1. A fluid bearing track structure or the like, comprising A. a groovedbar having a generally planar surface,

B. a series of spaced generally uniform grooves'in said surface,

1. said grooves being curved and extending across said surface,

2. each said groove being larger at one end thereof than at its otherend, whereby such groove is generally in the configuration of a curvednozzle, and

C. a back up bar engaged with said grooved bar in contact with saidsurface and closing off said grooves therein except at said endsthereof, whereby fluid introduced into each of said grooves through saidone end thereof may pass therethrough and "emanate from said other endthereof.

2. The track structure of claim 1 in which 3. each said groove in saidgrooved bar has a width which progressively decreases from one edge ofsaid surface toward the other edge thereof.

3. The track structure of claim I in which 3. each said groove ofgrooved bar has a depth which decreases progressively from one edge ofsaid surface toward the other edge thereof.

4. The track structure of claim 1 in which 3. each said groove of saidgrooved bar decreases progressively in both width and depth from oneedge of said surface toward the other edge thereof.

5. The track structureof claim 1 in which 7 3. each said groove of saidgrooved bar opens onto said other edge of said bar at an exit anglerelative thereto within a range of approximately lto approximately 25.

6. The track structure of claim 1 in which 3. each of said grooves ofsaid grooved bar opens onto said other edge of said bar generallytangentially thereof.

7. The track structure of claim 1 in which 3 each said groove of saidgrooved bar is formed generally as the segment of an ellipse.

8. The track structure of claim 1 which also includes D. a channelextending longitudinally of said grooved bar generally from one end tothe other end thereof,

a d 9113!???1. s g mias e edge qf a Surface in which said grooves areformed, 7

2. said back up bar in contact with said surface closing off saidchannelrand defining a fluid passing therewith.

9. The track structure of claim 1 which also includes D. a channelextending longitudinally of said grooved bar generally from one end tothe other end thereof one side of which defines one edge of saidsurface, and l E. another generally planar surface extending alonganother side of said channel,

s q as entiqasdar s e n free ta p vq 2. said back up bar in contact withsaid surface closing off said channel and defining a fluid passage

1. A fluid bearing track structure or the like, comprising A. a groovedbar having a generally planar surface, B. a series of spaced generallyuniform grooves in said surface,
 1. said grooves being curved andextending across said surface,
 2. each said groove being larger at oneend thereof than at its other end, whereby such groove is generally inthe configuration of a curved nozzle, and C. a back up bar engaged withsaid grooved bar in contact with said surface and closing off saidgrooves therein except at said ends thereof, whereby fluid introducedinto each of said grooves through said one end thereof may passtherethrough and emanate from said other end thereof.
 2. said back upbar in contact with said surface closing off said channel and defining afluid passage therewith.
 2. said back up bar in contact with saidsurface closing off said channel and defining a fluid passing therewith.2. The track structure of claim 1 in which
 2. each said groove beinglarger at one end thereof than at its other end, whereby such groove isgenerally in the configuration of a curved nozzle, and C. a back up barengaged with said grooved bar in contact with said surface and closingoff said grooves therein except at said ends thereof, whereby fluidintroduced into each of said grooves through said one end thereof maypass therethrough and emanate from said other end thereof.
 3. each saidgroove of said grooved bar has a depth which decreases progressivelyfrom one edge of said surface toward the other edge thereof.
 3. Thetrack structure of claim 1 in which
 3. each said groove in said groovedbar has a width which progressively decreases from one edge of saidsurface toward the other edge thereof.
 3. each said groove of saidgrooved bar opens onto said other edge of said bar at an exit anglerelative thereto within a range of approximately 1* to approximately 25*.
 3. each said groove of said grooved bar decreases progressively inboth width and depth from one edge of said surface toward the other edgethereof.
 3. each said groove of said grooved bar is formed generally asthe segment of an ellipse.
 3. each of said grooves of said grooved baropens onto said other edge of said bar generally tangentially thereof.4. The track structure of claim 1 in which
 5. The track structure ofclaim 1 in which
 6. The track structure of claim 1 in which
 7. The trackstructure of claim 1 in which
 8. The track structure of claim 1 whichalso includes D. a channel extending longitudinally of said grooved bargenerally from one end to the other end thereof,
 9. The track structureof claim 1 which also includes D. a channel extending longitudinally ofsaid grooved bar generally from one end to the other end thereof oneside of which defines one edge of said surface, and E. another generallyplanar surface extending along another side of said channel,